Effects of the blade number on the performance of a rocket engine turbopump inducer are investigated in the present paper. For that purpose, two inducers characterized by three blades and five blades, respectively, were manufactured and tested experimentally. The two inducers were designed on the basis of identical design flow rate and identical pressure elevation at nominal flow rate. The first part of the study focuses on the steady behavior of the inducers in cavitating conditions: evolutions of performance, torque, mass flow rate, and amplitude of radial forces on the shaft according to the inlet pressure are considered. Several flow rates and rotation speeds are investigated. Significant differences between the inducers are obtained concerning the critical cavitation number, the amplitude of the radial forces, and the organization of cavitation in the machinery. Cavitation instabilities are investigated in the second part of the study. Various flow patterns are detected according to the mass flow rate and the cavitation number.

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